DLT tape / no streaming

Konrad Heuer kheuer2 at gwdg.de
Wed Apr 20 00:16:09 PDT 2005


I use a Benchmark DLT tape drive to backup data on my DELL PowerEdge 2650
system; syslog says:

Apr 20 09:09:02 gwdu111 /kernel: sa0 at ahc0 bus 0 target 6 lun 0
Apr 20 09:09:02 gwdu111 /kernel: sa0: <BNCHMARK VS640 5032> Removable
Sequential Access SCSI-2 device
Apr 20 09:09:02 gwdu111 /kernel: sa0: 20.000MB/s transfers (10.000MHz,
offset 15, 16bit)

The problem I see is that data flow is not steadily streaming; the tape
drive is operating in start-stop-mode.

Disk speed does not seem to be the problem, e.g.:

gwdu111# dd if=/home/local2/ftp/pub/FreeBSD/3.3-RELEASE.iso of=/dev/null
82401+0 records in
82401+0 records out
675028992 bytes transferred in 14.670024 secs (46014170 bytes/sec)

What can I do to improve the situation? Any ideas are very welcome. Thanks
in advance!

Konrad Heuer
GWDG, Am Fassberg, 37077 Goettingen, Germany, kheuer2 at gwdg.de

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